75 % of 1,1 -dimethylhydrazine and 25 % hydrazine hydrate
Dinitrogen tetroxide, nitric acid, MON
UH 25 is a fuel mixture for missiles, which was developed for the Ariane 2-4.
After it had come to combustion instabilities in the second flight in a Viking engine of the first stage of an Ariane 1, which eventually led to the engine fire and failure launch of the rocket, it was decided to change the fuel. However, the change took place only on the more powerful versions Ariane 2 and Ariane 3, where they switched from pure UDMH on the fuel mixture UH 25. So they wanted to prevent such accidents in the future
The mixture was stirred at Ariane 2-4, and still used in the Indian rocket PSLV and GSLV. This use in India under license Viking engines made .
UH 25 is a blend of 75% and 25% hydrazine hydrate UDMH. Together with the oxidant to form a nitrogen tetroxide at normal temperatures storable hypergolic, toxic and corrosive fuel mixture. For similar components, there is a Aerozin 50th
UH 25 is like its ingredients hydrazine and UDMH toxic, corrosive and carcinogenic.